* {
    padding: 0;
    margin: 0;
    list-style: none;
}

.banner {
    width: 500px;
    height: 300px;
    margin: 50px auto;
    position: relative;
}




.banner ul li {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    background-color: #f00;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 50px;

    opacity: 0;
    transition: .3s;
}

.banner span {
    position: absolute;
    top: 0;
    bottom: 0;
    margin: auto;
    width: 30px;
    height: 30px;
    background-color: rgba(0, 0, 0, .5);
    color: #fff;
    text-align: center;
    line-height: 30px;
}

.next {
    right: 0;
}

ol {
    position: absolute;
    width: 100%;
    display: flex;
    justify-content: center;
    bottom: 0;
}

ol li {
    width: 20px;
    height: 20px;
    margin: 10px;
    background-color: #666;
}

.active {
    background-color: #ff0;
}

.show {
    opacity: 1 !important;
}